Lenghty in time, but a great challenge and a satisfied customer.
5 - 30 minutes
I was crazy about not being able to use the home button, running out of battery and not being able to sync nor properly charge my phone.
the repair took me a while, but in the end everything went swell.
Make sure that when replacing the home button, by the time you get to separate the screen from the body of the phone there's some stubborn glue right over the home button area. You might think you are missing a screw in there, but just be patient and work it nice and smooth and eventually you'll be able to tackle that glued portion surrounding the home button.
iPhone 4 Replacement Battery
iPhone 4 (GSM/AT&T) Dock Connector
iPhone 4 Home Button Assembly